Straining and sifting apparatus



Sept. 14, 1965 J. HURST STRAINING AND SIFTING APPARATUS 2 Sheets-Sheet 1 Filed July 16, 1962 Sept. 14, 1965 J. HURST 3,206,029

STRAINING AND SIFTING APPARATUS Filed July 16, 1962 2 Sheets-Sheet 2 United States Patent Oti ice 3,Z%,Z Patented Sept. 14, 1965 3,206,tl29 STRAINING AND SIFTING APPARATUS Eustin Hurst, London, England, assiguor to Russell Constructions Limited, London, England, a British company Filed July 16, 1962, Ser. No. 210,128 4 Claims. (Cl. 209-4665) This invention comprises improvements in or relating to straining and sifting apparatus.

It is known to manufacture strainers or sieves which comprise a horizontal straining or sifting septum mounted on a frame which is carried on depending suspension rods so that it can move freely in any direction in a horizontal plane and to attach to the frame an out-of-balance weight rotatable about a vertical axis and to rotate the out-of-balance weight at a high speedsay 1400' to 2000 or more revolutions per minute. The effect is that the septum vibrates with a circular movement of small amplitude which is elfective in assisting the straining or sifting action. The present invention relates to apparatus of this type.

It has now been found that in this apparatus superior results are obtained if the straining or sieving element is mounted on a sub-frame which is flexibly attached to the main part of the sieve-frame in a way which permits a slight up-and-down movement of the sieve element relatively to the main part of the sieve-frame and the present invention relates to an apparatus constructed in this way. The following is a description by way of example, of one construction in accordance with the invention.

In the accompanying drawings,

FIGURE 1 is a side elevation of the construction, partly in section, and

FIGURE 2 is a plan of a sieve-frame and sieve.

The apparatus is built up on a base 11 which is mounted on three trolley wheels 12, 13, one of which (12) is steerable and the steering rod of which is provided with a handle 14'. The base is constructed in the form of a ring-shaped casting to which are bolted brackets 15, 16 supporting the trolley wheels. Secured to the ringshaped casting is a framework comprising three equidistant stout upstanding posts 17 and bolted to the top of the posts, a horizontal frame-plate 18, the general shape of which is circular, but which extends out at one side to form a support 19 for a driving motor 20. The driving motor is bolted to the upper side of the frameplate and its shaft extends downwardly through a hole in the plate to a double-grooved V-pulley 21 below the plate. The frame-plate 18 carries a bearing 22 for an up right shaft 23 which is located with its axis concentric with the ring-shaped base 11 and the centre of the three posts 17 which carry the frame-plate. Below the frameplate 18 the shaft 23 carries a double-grooved V-pulley 24 driven by two V-belts 25 from the motor pulley 21.

Above its hearing the vertical shaft 23 carries a flange 26 forming part of a flexible coupling which is hereinafter further referred to. At a somewhat greater radius than the posts on which it is supported the frame-plate carries three hollow upstanding columns 27 constituting suspension supports, the bases of which are secured to the frame-plate by set screws 28 from beneath the frameplate, and are located above holes 29 cut through the frame-plate to coincide with the hollow interior of the columns. The columns 27 are located at points around the frame-plate 18 which are intermediate between the locations of the posts 17 on which the frame-plate is carried and they are used to support at their upper ends flanged metallic holders 30 containing rubber cushions. Through the rubber cushions pass the upper ends of suspension rods 31 which are secured in place by nuts 32, 33 above and below the cushions. The rubber cushions constitute a yielding anchorage means for the suspension rods. The suspension rods 31 extend downwardly from the hollow columns to a position well below the frameplate 18 and here they are connected to brackets 34 on a sieve-carrying-frame. Metallic cups 35 containing rubber cushions are again employed to anchor the lower ends of the suspension rods 31 to the brackets 34.

The sieve-carrying-frame comprises an upper angle iron ring 36 located in a horizontal plane above the tops of the hollow columns 27 which support the suspension rods 31 and having a diameter nearly double that of the circle on which the suspension rods are located. To the underside of this angle iron ring 36 there are secured three stout depending frame members 37, the upper ends of which are bent outwardly to engage the ring 36 but the main portions of which are vertical and the lower ends of which carry the aforesaid brackets 34 for engagement with the suspension rods. At about the level of the upper ends of the suspension rods these vertical members 37 of the sieve-frame have inwardly extending forked brackets 38 firmly bolted to them. Each bracket 38, as viewed in plan, is forked to form two arms 39 which extend inwardly, one on one side and the other on the other side of the adjacent hollow column 27 which supports one of the suspension rods 31, the arms of the brackets being wide enough apart not to touch the column 27. At their inner ends the arms of the brackets are united to an out-of-balance weight casing 40. Therefore, the out-of-balance weight casing 46 with the brackets 38, the vertical arms 39 and the large horizontal ring 36, all form a vibrating frame to support the sieve 41, which is removable and is shown in chain lines accordingly in FIGURE 1.

The out-of-balance Weight casing 40 is circular in plan and has a vertical shaft 42 in the centre which is coaxial with the flexible coupling member 26 above referred to and is supported in stout ball and roller bearings 43, 44 in the casing. Below the casing the shaft 42 carries a second flange member 45 of the flexible coupling and the two parts of the coupling are connected together by means including a rubber coupling ring 46 so that the coupling shaft 23 below the casing can drive the shaft 42 of the casing without interfering with small lateral displacements of the sieve-frame ring 36. Within the casing 40 on the vertical shaft 42 is a flywheel 47 which carries an out-of-balance weight 48, the position of which can be adjusted to vary the degree of out-ofbalance.

The large angle-shaped ring 36 which forms the upper member of the sieve-carrying-frarne has welded to it at three places intermediate between the points of attachment of the vertical members of the frame, outstanding flat plate brackets 50 in which are secured metallic cups 51 containing flexible rubber cushions similar to the cups 361, 35 which support the suspension rods 31. Above the angle-ring 36 of the sieve-frame is a second angle-ring 52 which forms a sub-frame and is spaced somewhat from the main part of the sieve-frame in a vertical direction. This second angle-ring 52 has an inwardly directed horizontal flange at the bottom whereas the first angle-ring 36 has an inwardly directed horizontal flange at the top. The two flanges face one another therefore, but, as stated above, are spaced apart. Horizontal plate brackets 53 secured to the underside of the sub-frame angle-ring eX- tend outwardly into engagement with bolts 49 which pass through the aforesaid rubber cushions in the cups 51 and thus the sub-frame 52 is flexibly supported from the main sieve-frame ring 36. A circular sieve surface 60 is secured inside the angle-ring 52 of the sub-frame and it is held taut by stiffening rings 59 around its edge which fit the sub-frame. It is secured to the sub-frame by a number of dogs 54 all round the periphery of the sub-frame 52 which are held down by bolts 55 and nuts 56. The rings to which the sifting surface is secured also carry below the sifting surface a shallow funnel 57 with a discharge chute 58 extending laterally at a slight downward inclination to one side of the machine. The sifting surface 60, which may be of fine wire mesh, is supported beneath by a light metal spider 63 secured to the rings 59 which clamp the sifting surface 60 and above the sifting surface there is within the outer wall 61 of the sieve-frame, an upstanding division wall 62 which is secured to the spider by bolts 64 passing through the sitting surface and which, as viewed in plan, follows a spiral course ending in contact with the outer enclosing wall 61 at 65. Where the spiral division wall 62 abuts against the outer wall there is a hole cut through the outer wall and from this, on the outside, there extends a discharge chute 66 for coarse material.

In operation this apparatus is run at a'high speed, for example, 2400 revolutions per minute, of the out-of-balance weight shaft 42. The effect is that the sieve-frame with its sub-frame and the sieve surface is caused to move with a small circular movement in a horizontal plane and is also caused to rock laterally. As a result, any given point of the edge of the sieve-frame will be seen to be moving in an inclined elliptical path which may have a longer axis of about inch and a shorter axis of about inch, the inclination being at about 30 or 45 to the horizontal. The actual amplitude of the vibration will depend of course upon the setting of the out-of-balance weight in relation to its fly-wheel.

It is found that the flexible connection of the sieve subframe 52 to the main sieve-frame 36 assists the rocking movement referred to and enhances it with the result that the feeding of material along the spiral guide wall 62 toward the outlet 66 is made more rapid, and, for example, the draining of water out of pulverulent material is also speeded up. Consequently the capacity of the sieve is increased.

Although reference has been made to a speed of 2400 revolutions per minute, with the particular apparatus described, speeds varying between 2000 revolutions per minute and 2800 revolutions per minute can be successfully employed and the best speed for a given material may require to be arrived at by a simple preliminary trial. The speed can be adjusted either by changing the diameter of the belt pulleys 21, 24 or by fitting a change speed gear.

I claim:

1. In sifting straining apparatus the combination of a base to which are secured a framework comprising at least three upstanding rigid suspension-supports disposed symmetrically about a central axis, yielding anchoring means on said supports, suspension rods anchored by said anchoring means to said supports and depending therefrom, a sieve-carrying frame comprising a ring normally concentric with said axis and located above the anchoring points of said suspension rods on the supports, depending framemembers extending downwardly from the ring, yielding anchoring means on the said depending frame members, serving to anchor them to the lower ends of the suspension rods, brackets on said depending frame-members secured to a flywheel casing coaxial with said ring and located at approximately the same level as the upper ends of the suspension rods, an out-of-balance flywheel in the flywheel casing, means for rotating the same, a sub-framering above the ring of the sieve-carrying frame, yielding means connecting the sub-frame-ring to the ring of the sieve-carrying frame to permit up-and-down yielding movements of the edges of the two rings relatively to one another, and a sieve-septum mounted on the sub-framering.

2. In sifting and straining apparatus the combination as claimed in claim 1, wherein the yielding means connecting the two rings together comprises outstanding flat brackets at intervals around the periphery of each ring and rubber buffers uniting the brackets together.

3. In sifting and straining apparatus, the combination as claimed in claim 2, wherein the radii of the two rings are of the order of approximately twice the radius of the suspension rods from the axis.

4. In sifting and straining apparatus, the combination as claimed in claim 2, wherein the sub-frame ring carries an outer wall upstanding around the sieve-septum and on the sieve-septum is a spiral guide-wall extending from a point near the center of the septum to a discharge aperture in the outer wall.

References Cited by the Examiner UNITED STATES PATENTS 690,731 1/02 J amieson 209366.5 1,354,319 9/20 Lowe 209332 2,540,517 2/51 Glasco 7487 XR 2,828,013 3/58 Hurst 209-366.5 3,047,151 7/62 Hurst 209366.5

FOREIGN PATENTS 913,125 4/54 Germany.

562,210 6/44 Great Britain.

574,410 1/ 46 Great Britain.

HARRY B. THORNTON, Primary Examiner.

HERBERT L. MARTIN, Examiner. 

1. IN SIFTING STRAINING APPARATUS THE COMBINATION OF A BASE TO WHICH ARE SECURED A FRAMEWORK COMPRISING AT LEAST THREE UPSTANDING RIGID SUSPENSION-SUPPORTS DISPOSED SYMMETRICALLY ABOUT A CENTRAL AXIS, YIELDING ANCHORING MEANS ON SAID SUPPORTS, SUSPENSION RODS ANCHORED BY SAID ANCHORING MEANS TO SAID SUPPORTS AND DEPENDING THEREFROM, A SIEVE-CARRYING FRAME COMPRISING A RING NORMALLY CONCENTRIC WITH SAID AXIS AND LOCATED ABOVE THE ANCHORING POINTS OF SAID SUSPENSION RODS ON THE SUPPORTS, DEPENDING FRAMEMEMBERS EXTENDING DOWNWARDLY FROM THE RING, YIELDING ANCHORING MEANS ON THE SAID DEPENDING FRAME MEMBERS, SERVING TO ANCHOR THEM TO THE LOWER ENDS OF THE SUSPENSION RODS, BRACKETS ON SAID DEPENDING FRAME-MEMBERS SECURED TO A FLYWHEEL CASING COAXIAL WITH SAID RING AND LOCATED AT APPROXIMATELY THE SAME LEVEL AS THE UPPER ENDS OF THE SUSPENSION RODS, AN OUT-OF-BALANCE FLYWHEEL IN THE FLYWHEEL CASING, MEANS FOR ROTATING THE SAME, A SUB-FRAMERING ABOVE THE RING OF THE SIEVE-CARRYING FRAME, YIELDING MEANS CONNECTING THE SUB-FRAME-RING TO THE RING OF THE SIEVE-CARRYING FRAME TO PERMIT UP-AND-DOWN YIELDING MOVEMENTS OF THE EDGES OF THE TWO RINGS RELATIVELY TO ONE ANOTHER, AND A SIEVE-SEPTUM MOUNTED ON THE SUB-FRAMERING. 